Conventionally, an engine system including an internal combustion engine as a main component is frequently provided with a turbocharger with an exhaust turbine. Furthermore, a cooling system has been proposed to be provided in such an engine system to cool not only the internal combustion engine but also the exhaust turbine (specifically, a turbine housing for the exhaust turbine) (see Patent Document 1). The apparatus described in Patent Document 1 is configured such that coolant flows from an engine coolant path inside the internal combustion engine into a turbine coolant path inside the turbine housing. Cooling with the coolant keeps the temperature of the turbine housing at an appropriate value.